1. Field of the Invention
The present invention relates in general to swash plate compressors, and more particularly to a method of producing pistons used in the swash plate compressors.
2. Description of the Prior Art
Swash plate compressors are widely used in an automotive air conditioners for the reason of high efficiency. In the swash plate compressors, there are generally two types, one being a fixed displacement type wherein a swash plate is fixedly mounted on a rotation shaft and the other being a variable displacement type wherein a swash plate is pivotally mounted on a rotation shaft. In both types of compressors, pistons in respective cylinders are reciprocatively driven by a swing motion of the swash plate under rotation of the rotation shaft.
Some of the swash plate compressors of the above-mentioned types are of a so-called "piston direct connection type" wherein each piston is directly but slidably engaged with a peripheral portion of the swash plate without usage of a separate piston rod. In the compressors of such piston direct connection type, single headed pistons are commonly used, which includes each a piston head portion slidably received in a corresponding piston cylinder and a generally U-shaped neck portion slidably engaged with the peripheral portion of the swash plate.
For achieving the slidable connection between the U-shaped neck portion and the peripheral portion of the swash plate, a structure is commonly employed wherein two spherical shoes are slidably put in spherical recesses formed on opposed inner surfaces of the U-shaped neck portion and the peripheral portion of the swash plate is slidably sandwiched between the shoes.
That is, front and rear flat surfaces of the plate's peripheral portion are slidably engaged with flat surfaces of the shoes respectively. Thus, upon rotation of the rotation shaft, the swash plate is forced to make a swing motion around the rotation shaft thereby inducing a reciprocative motion of each piston in the corresponding piston cylinder.
As will be understood from the above, the pistons used in the compressors of the piston direct connection type are important functional parts which need high dimensional accuracy and light weight construction in addition to high productivity.